Endocrine Disrupters

Eva Cecilie Bonefeld-Jørgensen Professor, Director, PhD

Centre for Arctic Health & The Unit of Cellular and Molecular Toxicology

Department of Public Health Aarhus University

Outline of the talk

• Endocrine disrupters (EDs) o Sources,

o Exposures

o Mechanisms

• Endocrine disrupters (EDs) o Effects

The Endocrine systems are targets

of endocrine disrupting chemicals

• The endocrine system

consists of hormone

producing glands.

• The hormones are

released into the

bloodstream and are

involved in basic body

functions:

• Growth, metabolism,

reproduction, sexual

development and

behavior

From: Endocr Rev. Jun 2009; 30(4): 293–342. doi: 10.1210/er.2009-0002

Signal pathways

between cells

• Endocrine signaling: hormones produced by the hormone glands travel long distance via the bloodstream

• Paracrine signaling: local, affecting nearby cells

• Neuronal signaling / synaptic: via nerves, fast signals, neurotransmitter binds to receptors

Steroid Hormones Fat-soluble hormones (steroids) binds to transport proteins and are transported via the blood stream to the organ/tissue to act where they binds to intracellular receptors and affect the cell's protein synthesis

What is Endocrine Disrupting

Chemicals EDCs • Normal hormones are responsible for the maintenance

of homeostasis, growth, reproduction, development and behavior

• EDCs are chemicals that can mimic and interfere with normal hormones o Synthesis, secretion, transport, binding, function (activity), or elimination from

the body

o thereby, block and / or interfere with hormone-related functions

• EDCs can be found everywhere, water, air, food, and dust o So we are exposed to them daily through our environment and food

• Several EDs are resistant to degradation in the environment and the organisms (animals- human).

• Thus they are persistent and therefore bio-accumulate in body tissues and / or adipose tissue.

Examples of EDCs • Persistent organochlor/brom/fluor compounds

(POPs) bio-accumulate

• Primarily in fat o Dioxins and Polychlorinated Biphenyl's(PCBs)

o Pesticides, organochlor pest.(DDT/DDE),

o Brominated flame retardants

• Primarily in organs o Perfluorinated compounds (PFCs)

• Non-Persistent o An array of currently used pesticides

o Plastic Components

• Bisfenol A (xeno-estrogen) (plastic lining in food cans, dental composite fillings, baby bottles)

• Phthalater (xeno-androgens)(Plastic softener in e.g. PVC, cosmetics, paints, glue)

• Octylphenols (degradation product of alkylphenol ethoxylates)

o washing powder / cosmetics / paint / pesticides

o Phytoestrogens ( xeno-estrogen) (e.g. soy products genistein and daidzein)

testosterone Tyroxine T4

PCBs

dioxin

prochloraz

Bio-accumulation up through

the food chain

Lipophilic POPs:

PCBs (PolyChlorinated Biphenyls), dioxins (T1/2 op til 10 år)

Organochlor-pesticides (OCP) e.g. DDT/DDE (T1/2 op

til 5 år).

De ”amphiphillic” – both vater and fat repellent

PerFlouroalkyl Compounds (PFACs) (T1/2 4-8 år):

8

HFS 17-03-16

Perfluoroalkylated Substances (PFAS)

Bio-accumulate in animals (T1/2: 4t-150 days) and humans (T1/2: 4-8 years)

Endocrine Disriupters

EDCs Characteristic Source Effects Structure

Dioxins

fx 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

Lipophilic Food Inhalation

By-products of combustion; paper production, PVC plastic production; preservative wood, textiles, paint, glue and others.

Immune suppressive acute toxic Affects CNS and sexual development / de-maskulination Disturbs thyroid hormone Anti-estrogen carcinogen

PCB

Lipophilic Food Inhalation

Lubricants, coolant, transformer oil, adhesives, plasticizers, sealants

Reduced IQ (learning) Immune suppressive Reduced birth weight (Anti)-estrogen / androgen Carcinogen

Organochlor pesticides: DDT,

endosulfan, dieldrin, endrin, aldrin, mirex, heptachlor, kepone, dicofol, chlordane, pentachlorophenol

Lipophilic (both /and) Food Inhalation Skin

Insecticides and fungicides: Agriculture, horticulture, wood products, etc.

Reproductive and Developmental Disorder Acute toxic Diabetes Carcinogen

Brominated

Flame retardant

Lipophilic Food Inhalation

Electronics, plastics, textiles, furniture

Reproductive and Developmental Disorder

Perfluorinated Compounds

Amphiphilic: Organs Water, dust, food, textiles

Impregnating products: textiles, shoes, pots and pans, food packaging etc.

Decreased fertility Reduced birth weight Immune suppressive Carcinogen

Metaller: arsenic, cadmium, lead, mercury

Cd Food, Smoking

Industry / mining, electronics / agriculture / Waste Incineration

Neurotoxic, Reproductive Disorders Neurotoxic / Reduced IQ

As, Cd, Pb, Hg

DDT

dieldrin

Persistent Endocrine Disrupters (EDCs)

Important differences between normal hormones and endocrine disruptors

Normal sex steroid hormones is bound to the steroid hormone binding globulin (SHBG) in an

inert stage

Environmental xeno-estrogens e.g. POPs accumulate in the food chain and tissue / fatty tissue of

humans and animals

since they generally do not bind to SHBG they achieve a higher bio-available concentration

Phytoestrogens are rapidly degraded, have often anti-estrogen effect, can induces

SHBG production and thus improve hormone homeostasis

In Utero Exposure to Dioxins and Dioxin-like

Compounds and Anogenital Distance (AGD) in Newborns and Infants

• Aim: Assessment whether in utero exposure to dioxins and dioxin-like compounds

adversely influences AGD in newborns and young children (median age, 16 months;

range, 1–31 months).

• Method: Measurement of the AGD (AGD; anus to upper penis / back vagina)

among participants of the “Rhea” mother–child cohort study in Crete and Barcelona.

Plasma dioxin-like activity in maternal blood at delivery

• Results

o AGD distances were sexually dimorphic, being longer in males than females.

o Plasma dioxin-like activity was negatively associated with AGD in male newborns.

o The estimated adjusted change in AGD per 10 pg CALUX®–toxic equivalent/g lipid

increase was –0.44 mm (95% CI: –0.80, –0.08).

o Negative non-significant associations were observed for AGD in young boys.

o No associations were found in girls.

• Conclusion: Male infants may be susceptible to endocrine-disrupting effects of

dioxins (Marina Vafeiadi et al. 2013)

• Drinking water and dust

• Contaminated foodstuff

• Inhalation

• Intravenous tubing equipment used for newborns / children

• Toys, for example. vinyl products

• Personal care products

• Medicine - pills

o Some medical pills for oral ingestion are coated with phthalates

to control pill solution

o Phthalate esters used in bags for storage of packed red blood

cells can cause exposure

o Shown to activate the release of pro-inflammatory cytokines

(Leonard et al. 2009)

Sathyanarayana et al 2008 Plastic Materials / phthalates

Phthalates: Often xeno-(anti)androgens

Phthalates: In utero and lactation Reproductive effects in rats

• Plasticisers: o Dietylhexyl- (DEHP)>, butylbenzyl- (BBP)>, dibutyl- (DBP)>,

diisoninyl phthalate (DINP)

• Dosis-related effects o (375-1,500mg/kg/dag per os)

• Abnormal sexual development of male rat o Anti-androgen o Reduces testosterone to female rat level o Decreases central nerve system development o Feminization o Hypospadias, cryptorchidism, abnormal prostate development o Reduced birth weight and testes weight

ECBJ, Rovaniemi, October 2002

EBJ 2000

Effect mechanisms of xeno-hormonesReceptor

Hormone

Normal hormone

response

X X can inhibit or block

normal hormone

response

Hormone

HH

HH

HHHormone

Additive or synergistic

effects between toxicant

and hormone

HH Endogenous Hormone

X

X

XX Toxicant

XXToxicantXeno-hormone

response

EDC

Xeno-hormone response

The pesticide Prochloraz can down regulate the expression of ERa and ERb mRNAs and

the ERa protein level • Background: Exposure to endocrine disrupters such as dioxins, PCBs and

certain pesticides are suspected to affect human reproductive health.

• Method: on-line RT-PCR quantification of the ERa and ERb mRNA levels in

the human breast cancer cell line, MCF7-BUS. Western blot analyses

• Results: Exposure with E2 or prochloraz decreased ERa and ERb mRNAs

after 48 h of treatment. Co-treatment with the ER antagonist ICI 182,780

abolished these mRNA down regulations.

• A decreased ER protein level after 3 h of exposure with prochloraz was

found but after 24 h the ERa protein level had recovered to basal level

Fig.2. Western blot analyses of the ERa protein (67 kDa) level in MCF7-BUS cells after treatment with E2 (10 nM), ICI 182,780 (ICI) (100 nM) and prochloraz (10 lM). ER a protein level after exposure with chemicals for (a) 3 h and (b) 24 h. Keratin no.7 (K7) (40 kDa) was used as an internal control.

Hofmeister & Bonefeld-Jørgensen. Toxicology in Vitro 18 (2004) 427–433

Exposure to EDCs and risk assessment • Exposure concentrations, the dose-response reactions may be non-

monotonic and thereby may result in low doses is more potent than higher

doses vice versa

• No-adverse-effect-level (NOAEL) assumes monotonous dose-response

• Exposure to individual substances vs. complex mixtures:

o Single compound principle in exposure are used today in risk assessment,

although the illustrated cocktail effects of mixtures of many EDCs (more than

additive or "synergism“

• Latency between exposure and adverse health outcomes

o Exposure in fetal life can cause diseases / effects later in life

• Preventive strategies

HFS: hormonforstyrrende stoffer

Individual sensitivity • The genetically background

Is different between individuals

• This cause individual

differences in sensitivity to

exposure and disease

Genes, age, nutrition, lifestyle

DNA kromosomer

Examples of where traditional risk assessment has not worked

• Diethylstilbestrol (DES), pregnant women (1940 to 1970);

o 1st. Breast cancer, 1st., 2nd. and 3rd endocrine disruption, decreased fertility, vagina cancer in offspring

• Thalidomide, pregnant women (1960ies; morning sickness, no effects in rat experiments)

o structural malformations in the baby

• Perfluorinated compounds (PFCs), (1950’ies)

o Reproductive disorders, organ toxicity, carcinogenesis

Celle kultur Gene og protein

ekspression, oxidative stress Rat exposure ADME

ADME: Adsorption, Distribution, Metabolism, Excretion

Three generations at once are exposed to the some environmental conditions (diet, toxics, hormones, etc.). In order to provide a convincing case for epigenetic inheritance, an epigenetic change must be observed in the 4th generation. Pedera and Herbstman, Reprod toxicol 2011 (31,3)

Prenatal environmental exposures,

epigenetics, and disease

Model of epigenetic modifications according to current knowledge

Nowsheen et al. Cancer Letters, Vol.342 (2) 2014.

21 Gene silencing

Gene activation

What is Genomic Imprinting?

• Genomic imprinting (GI) is an epigenetic process resulting in

parent-of-origin specific mono-allelic expression

• The majority of GI genes (~80%) are linked in a cluster meant

to facilitate coordinated regulation

• A single genetic / epigenetic change in an imprinting control

region can consequently result in disruption of many genes

• Deregulation of GI is associated with pre-natal lethality in mice

and many pathologies in humans ranging from behavioral

disorders to cancer

• Epigenetic modifications are inherited at the somatic-cell

division level and can be found in subsequent generations

Pagona Lagiou, Onc . 2007

22

DNA methylation, has been associated with cancer initiation and progression.

POPs decrease DNA methylation in humans

• In utero exposure to xeno-estrogens, assed by isolated lipPOPs from placentas, decrease global DNA methylation of repetitive elements for placentas of boys but not for girls.(Vilahur et al.2014; Env, Internal.)

• In utero (cord blood) exposure to PFOA, to less degree PFOS, was inversely correlated with Global DNA methylation. (Guerrero-Preston et al 2010; Epigenitics)

• In high exposed adult Inuit the level of serum PCB and persistent

organochlor-pesticides (OC) was significantly inverse correlated to global methylation Rusiecki et al. Environ Health Perspect (2008).

• In low-dose exposed adult Koreans the level of serum OC pesticides and to some degree PCB and PBDE, was inverse associated with global DNA methylation.(Kim et al. Environ Health Perspect . 2010).

POP: persistent organic pollutants

23

Suspected effects of endocrine-disrupting pollutants on human health especially by exposure

during fetal life

Reproduction: Reduced fertility (decreased sperm count, increased TTP (time to pregnancy)

Birth defects (cryptorchidism, hypospadias, changes in AGD,

reduced birth weight)

Increased risk of testicular and breast cancer

Puberty and Menstrual Disorders

Immune system defects

Reduced vaccination response, frequent infections

Central nerve system

Thyroid hormone disruption / Decreased IQ

Behavioral abnormalities (Autism, ADD / ADHD, reduced learning)

Change in metabolism (carcinogen induction) Endometriosis vs. reproduction Diabetes type 2? Parkinson desease ?

http://medical-dictionary.thefreedictionary.com/cryptorchidism

kryptorkisme

hypospadi,

AGD: anogenital distance VMS tema 22-10-15 24

Question

What is an endocrine disruptor?

Hormonforstyrrende stoffer